One thing is certain: standing there waiting to be noticed is not working for you.
Try approaching someone without seeming desperate, and just ask when the "A" bus arrives, how lovely the weather seems, etc. And leave it at that. Then repeat it until the conversation deepens naturally.
At 50+ with no vengeful divorced wife, no needy children, no major debts or vices, you are a valuable 'commodity' on the social whirl. Join a club, go to a church, drop into the senior center, get involved in politics or animal rights, you will meet someone you like who also likes you. Learn some conversation skills and stay away from negative topics until after the fifth or sixth date.